Measuring beyond the microscope field of view using digital images in squamous cell carcinoma of the lip

OBJECTIVE: To study the impact of using digital images for measuring the si ze of the tumors, assisting with the prognostic evaluation of carcinomas of the oral mucosa. STUDY DESIGN: The depth of invasion of 12 cases of squamous cell carcinoma of the lower lip was assessed through a microscope and through digital imag es. All measurements of depth of invasion were assessed in a direction orth ogonal to the lip surface. First, assessment of depth of invasion was done at the microscope, using an eyepiece reticule with an engraved scale. Secon d, depth of invasion was assessed by digital images, using a program module developed to assist pathologists with linear measuring. When the depth of the tumor was larger than the field of view at the proper magnification, se veral images were taken to include the whole area of invasion. The images w ere finally mounted in a single image and the depth of invasion measured. RESULTS: The results show positive and negative differences between assessm ents when assessing depths of < 2 mm. At greater depths ( greater than or e qual to 2 mm), the difference was always negative, showing that for deep in vasion, measurements of longer distances were always performed on digital i mages. CONCLUSION: Measurements with digital images beyond the field of view at pr oper magnification could significantly alter the diagnostic and prognostic assessment made using the microscope.